The present disclosure relates to process control systems. In particular, the present disclosure relates to wafers and flanges in industrial processes.
In processing plants, fluids are conveyed through piping to various processing elements. The piping includes individual pipe sections that are connected together by fittings. Elements, such as sensors and valves, can be introduced into the piping by placing the elements between the fittings of two pipe sections.
In a common configuration, a wafer is placed between two pipe sections. The wafer includes an outer ring that is positioned annularly about at least one fluid flow passage. One or more holes pass through the outer ring in a radial direction. Sensors may be introduced through the radial holes to interact with the fluid and/or piping may be introduced into the radial holes to direct fluid to a sensor mounted outside of the piping. Further, orifice plates, averaging pitot tubes, other flow obstructions or other components that interact with the process fluid may be positioned within the fluid flow passage of the wafer ring.
Some wafers are installed between process pipes by sandwiching the wafer ring between two flange fittings that are then connected together by nuts and studs or bolts. Flange fittings generally include a collar that is welded to the end of a pipe, a bore that is aligned with the inner bore of the pipe, an annular sealing section that extends around the bore and a flange section that extends around the annular sealing section. The flange section includes a planar face that has several through holes that accept studs for connecting the fitting to another fitting. The annular sealing section has a sealing face designed to mate with and seal against one or more other elements at the fitting junction.
Measurement devices that utilize wafers have a stated accuracy level for the measurements they provide. However, these accuracy levels are only valid if the wafer ring is properly centered relative to the center of the neighboring pipe sections. If the center of the wafer ring is offset from the center of the pipe section by more than a specified off-center allowance, the measurement device will not be able to provide measurements at the stated accuracy.